A MCh Test Pre-post Esophageal Acidification in Detecting GER-related Asthma

Abstract

The direct effect of gastro-esophageal reflux (GER) on lung function is still debated. Objective. To investigate the role of esophageal acidification in affecting airway response to MCh in GER-related versus atopic asthmatics and to assess specificity and sensitivity of events. Subjects. A total of 56 never-smoking, mild asthmatics: 27 non-atopic asthmatics and acid GER (GER+ve) and 29 atopic asthmatics without any GER (GER–ve). Methods. Each subject performed an MCh challenge in baseline (MCh_b), and 30 minutes after an acid drink (125 mL at pH = 2; MCh_ac), one day apart. PD₂₀FEV₁ MCh_b and MCh_ac were compared by estimating the area under the ROC curve (AU-ROC). Results. GER+ve and GER-ve subjects (well matched in baseline) had a different duration of esophageal acid contact (24-hour monitoring; pH-24h AU₄), and PD₂₀FEV₁ MCh_ac (both p < 0.001). AU-ROC was 86.3% (76% to 97%, 95%CI). Sensitivity and specificity of changes were 82.8% (72.9% to 92.7%, 95%CI) and 85.2% (75.9% to 94.5%, 95%CI), respectively. The difference in MCh threshold that maximized both the sensitivity and specificity level was 100 μ g. Conclusions. The esophageal acidification identified GER-related asthma with a good level of both sensitivity and specificity by enhancing the MCh response only in the presence of acid GER. Data are supporting the effectiveness of this procedure for clinical purposes.

Keywords:

• gastro-oesophageal reflux
• bronchial asthma
• bronchial hyperreactivity
• lung function
• GER-related asthma
• oesophageal acidification